Laser Beam Welding - Mohamed Mostafa

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Under Supervision of Dr.Ing Islam El-Galy Laser Beam Welding (LBW) of Aluminum Alloys PE – 225 Material Technology -2 Course Mini Project

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Laser Beam Welding (LBW) of Aluminum Alloys

Transcript of Laser Beam Welding - Mohamed Mostafa

Page 1: Laser Beam Welding - Mohamed Mostafa

Under Supervision of

Dr.Ing Islam El-Galy

Laser Beam Welding (LBW) of Aluminum Alloys

PE – 225 Material

Technology -2

Course Mini Project

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Contents

LBW Principle

Advantages of Laser Welding

Limitation of Laser Welding

Case Study

Conclusion

Laser Beam Welding

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Welding

Forge

Welding

Fusion

Welding

• LBW is Fusion Type Welding

Laser Beam Welding

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LBW Principle

Laser is an acronym for light amplification by stimulated emission of radiation.

Laser Beam Welding (LBW) is a fusion joining process that produces coalescence of materials with the heat obtained from a concentrated beam of coherent, monochromatic light impinging on the joint to be welded

Laser Beam Welding

Source : Applications of Lasers in Materials Processing by Metzbower

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Laser Welding

Solid-State

Laser

Gas

Discharge

Laser

Laser Beam Welding

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LBW Principle

Laser Beam Welding

Source : ISF aachen

Gas Discharge Solid State

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Advantages of LBW Low possibility of HAZ in the joint

No need for filler metal

Reduce Latency

No tool wear

LBW is not influenced by magnetic fields

Laser Beam Welding

Source : Applications of Lasers in Materials Processing by METZBOWER

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Limitations of LBW Joints must be accurately positioned

Maximum weld penetration is limited (19-21mm)

High reflectivity and high thermal conductivity of

materials like Aluminum effect the weldability of

the joint

Case Study

Laser Beam Welding

Source : Applications of Lasers in

Materials Processing By METZBOWER

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Objective

We need to increase the density of the laser

beam to overcome the welding problems

( reflectivity , heat conductivity ) which is

achieved by increasing the power as given

in the formula –

𝐵𝑒𝑎𝑚 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑃𝑜𝑤𝑒𝑟

𝐴𝑟𝑒𝑎 𝑋 𝐶

And as a result of high focus finer grains are

produced

Laser Beam Welding

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Aluminum Alloy 5456

Laser Beam Welding

Chemistry Data

Aluminum Balance

Chromium 0.05 - 0.2

Copper 0.1 max

Iron 0.4 max

Magnesium 4.7 - 5.5

Manganese 0.5 - 1

Silicon 0.25 max

Titanium 0.2 max

Zinc 0.25 max

Applications

• Pressure Vessels

• Marine Applications

Source : Aluminum.org

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Choosing Laser Machine Specifications MW 120 MW 160 MW 300 MW 400

Wavelength 1064 nm 1064 nm 1064 nm 1064 nm

Lasertype Nd.:YAG

flash lamp

Nd.:YAG flash

lamp

Nd.:YAG flash

lamp

Nd.:YAG flash

lamp

Mean Power 120 Watt 160 Watt 300 Watt 400 Watt

max. Pulse

Energy

80 Joule 120 Joule 120 Joule 120 Joule

max. Peak Power 9 kW 13 kW 13 kW 13 kW

Pulse width 0.5-20 ms 0.5-20 ms 0.5-50 ms 0.5-50 ms

Pulse Frequency 0.5 to 20 Hz 0.5 to 20 Hz 0.5 to 100 Hz 0.5 to 100 Hz

Focus Diameter 0.2 - 2.0 mm

motorized

0.2 - 2.0 mm

motorized

0.2 - 2.0 mm

motorized

0.2 - 2.0 mm

motorized

Focal Distance 100 mm 100 mm 100 mm 100 mm

Cooling System Water/Air

integrated

Water/Air

integrated

Water/Air

external

Water/Air

external

Laser Beam Welding

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Laser Machine

Laser Beam Welding

Sigma Laser Welding Machine

MW 400 Series

Special features:

• Pulse shaping for

welding special alloys

to make near perfect

welds on highly

reflective materials .

• Variable density of Laser

Beam according to high

peak pulse power

Source : Sigma Laser GmbH

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Metallographic Examination

Transverse cross sections were cut from the weldments for metallographic examination.

Specimens were polished with diamond powder less than 1 μm

Electron Beam Microprobe Analysis

Laser Beam Welding

Fracture surface of DT specimen Typical pore of the fracture surface of

a DT specimen of a laser weld

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Metallographic Examination

Laser Beam Welding

Fine grained Al solid solution in fusion

zone of Al 5456 laser weldment.

Representative microstructures of the fusion zone

and the base metal .

The microstructure of fusion

zone is considerably finer

than that for the base

metal.

This is attributed to the fact

that laser beam is a very

high density power source.

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Conclusion More than 90% of the precipitates are vaporized during

laser beam welding

Both the tensile strength and ductility of the laser beam

weldments are lower than the base metal properties.

The toughness values (DT energy) of the laser beam

weldments are superior to the base plate values due to

the fusion zone purification mechanism and refined

structures.

Laser Beam Welding

Source : D. W. MOON AWS Publications 1983

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Thank You

Laser Beam Welding